As is known in the art, syringes are medical delivery devices utilizable to administer a medicament to a patient. Syringes can be shipped empty in a sterile state and filled by an end-user, for instance, from a vial or other source of medicament at the time administration of the medicament is desired. Alternately, syringes can be of the prefillable form, wherein a set dosage of medicament can be pre-filled into the syringe by a pharmaceutical manufacturer for distribution to the end user.
In either case, syringes typically include a barrel portion adapted to retain the medicament. The barrels are normally configured of plastic or glass materials. The distal end of the barrel is normally configured to mate with a conventional piercing element, such as a pointed needle cannula made of steel or like material or a blunt ended cannula formed of plastic, to deliver the medicament contained in the barrel. In some syringes, the piercing element is attached to the syringe as an integral part of the distal end of the syringe barrel. An example of such a syringe is the HYPAK.RTM. brand prefillable syringe manufactured by Becton Dickinson Pharmaceutical Systems of Le Pont de Claix, France.
In other syringes, the piercing element is attached to the syringe when use of the syringe is desired. There are a number of basic kinds of such syringes. An example of such a syringe is the luer tip syringe. In a luer tip syringe, the hub of a piercing element is connected to a luer tip associated with the syringe. Another type of such syringe is the luer lock syringe. In a luer lock syringe, the luer tip is surrounded by a threaded collar. The hub of the piercing element is inserted over the luer tip and threadedly engaged to the collar.
In any of the aforementioned syringes, a plunger rod is inserted through the open distal end of the syringe barrel and, through its engagement with an elastomeric or rubber-like stopper element fitted in a fluid-tight manner within the interior of the barrel, a user can apply manual force to the plunger to deliver the medicament through the piercing element.
Whether the syringe is of the type that will be filled by the end user, or whether the syringe is of the prefillable type that is to be filled by a pharmaceutical manufacturer, there is a need to maintain the sterility of the syringe until such time as it is used to deliver a medicament. Where the syringe is of the prefillable type, it is also important to maintain the sterility of any drug stored within the barrel until such time as use of the drug is desired. It is further necessary in prefillable syringes to provide a fluid seal such that the medicament does not leak from the syringe barrel. For instance, where the syringe has a fixed needle, such as the HYPAK.RTM. brand prefillable syringe, a rubber needle guard is inserted over the piercing element. The needle guard seals the fluid path to the drug held in the syringe barrel while at the same time protects the medicament against contamination.
Another prior art approach for providing a fluid seal and for maintaining the sterility of a syringe is illustrated in FIG. 1. Here, a luer lock syringe 10 is depicted, and it includes a barrel 16 characterized by a proximal end 14 and a distal end 12. A luer collar 18 is formed adjacent the distal end of the syringe barrel. Luer collar 18 is characterized by a plurality of internal threads 20. As is true of luer lock syringes, a luer tip 22 conventionally extends beyond the distal end of luer collar 18, and is disposed for fluid communication with interior portions of the syringe barrel. Each of the syringes is typically provided with a plastic luer lock tip cap 24 to seal luer tip 22. Internal portions of luer lock tip cap 24 are configured to receive luer tip 22 and to mate with the exterior surface of luer tip 22. Luer lock tip cap 24 includes one or more threads 26 configured to mate with internal threads 20 associated with the luer collar.
While generally sufficing to provide a fluid seal and to maintain the sterility of various components of the syringe, including the luer tip and the interior of the syringe barrel, certain improvements can be realized to the aforementioned approach. Generally, external means of tamper evidence are necessary, in that the luer lock tip cap is threadedly engaged with the luer collar, and relying on the threaded structure alone, it is difficult to detect if the tip cap has been threadedly disengaged from the luer collar. Also, owing to frictional forces between the plastic parts, and depending on how tightly the luer lock tip cap is applied to the collar, it can be difficult to remove the luer lock tip cap from the luer collar. Moreover, while the luer lock tip cap is a relatively small unit, it would be beneficial to further minimize the quantity of waste which has to be disposed of after the syringe is used.